The value of that stake, between US$20 billion and $30 billion today, far exceeds the value of the rest of Yahoo.

Estimates of the worth of Yahoo's core Internet business vary greatly, but many put it at between $4 billion and $8 billion.

Twitter had about $3.6 billion of cash in hand at the end of the first quarter, so an acquisition of that scale wouldn't be such an outrageous idea.

But Twitter seems not to have taken its bid particularly seriously, according to the Post: While Yahoo CEO Mayer met Twitter officials, that company's CEO Jack Dorsey was not among them.

"When your CEO doesn't show up for a management meeting, you have to wonder how serious it was," a source told the Post, adding that the interest was speculative rather than driven by some grand strategy.

The companies are at least in agreement on one thing: Representatives for both quickly responded to questions about the Post story with the same message: "We don't comment on rumor and speculation."

Yahoo also owns about a third of Yahoo Japan, a joint venture with Japanese Internet company SoftBank. That stake is said to be worth around $8 billion. SoftBank is also an investor in Alibaba.

SoftBank is unlikely to be among Yahoo's suitors, though. It has an appetite for U.S. companies (it owns a majority stake in Sprint) but is short of cash at the moment. Earlier this week, it sold part of its stake in Alibaba back to the company.